System and method for primary point handovers

ABSTRACT

A method for operating a multiple point (MP) controller includes receiving, from a source primary point, a handover required message for a user equipment coupled to the source primary point, the handover required message including target primary point information and MP radio bearer information. The method also includes determining an MP configuration according to the handover required message, and sending, to a target primary point, a handover request message including the MP configuration and the MP radio bearer information. The method further includes sending, to the source primary point, a handover message including the MP configuration, the MP radio bearer information, and reconfiguration information for the user equipment, the handover message initiating a handover of a subset of the MP radio bearer from the source primary point to the target primary point, and receiving, from the target primary point, a handover complete message.

This application is a reissue application of U.S. Pat. No. 8,724,590.More than one reissue application has been filed for the reissue of U.S.Pat. No. 8,724,590. The reissue applications are (1) the presentapplication, U.S. patent application Ser. No. 14/876,481, and (2) U.S.patent application Ser. No. 16/002,213, which is a divisional of thepresent application, and also an application for reissue of U.S. Pat.No. 8,724,590.

TECHNICAL FIELD

The present invention relates generally to digital communications, andmore particularly to a system and method for primary point handovers.

BACKGROUND

In order to achieve better channel utilization and increase overallperformance, multiple transmission and multiple reception antennas (alsocommonly referred to as multiple input, multiple output (MIMO)) at bothevolved Node B (eNB) (or base station (BS), Node B (NB), communicationscontroller, and the like) and User Equipment (UE) (or mobile station(MS), terminal, user, subscriber, subscriber equipment, and the like)are considered.

An extension to MIMO makes use of multiple communications points (eachof which may be a set of geographically co-located transmit or receiveantennas) to transmit or receive to or from a single UE or a group ofUEs. As an example, the transmissions from the multiple transmissionpoints may occur at the same time and/or the same frequency, or they mayoccur at different times and/or at different frequencies so that the UE(or the group of UEs) will receive transmissions from all of themultiple transmission points over a time window. This operating mode mayoften be referred to as multiple point transmission. As an example, at afirst time, a first transmission point may transmit to a UE, at a secondtime, a second transmission point may transmit to the UE, and so on.Here the second time may or may not be the same as the first time.

Coordinated multiple point (CoMP) transmission is one form of multiplepoint transmission, wherein the transmissions made by the multipletransmission points are coordinated so that the UE or the group of UEsmay be able to either combine the transmissions made by the multipletransmission points or avoid interference to improve overallperformance. A transmission point may be an eNB, a part of an eNB (i.e.,a cell), a remote radio head (RRH) connected to an eNB, or so on. It isnoted that sectors of the same site, e.g., an eNB, correspond todifferent transmission points. Similarly, CoMP reception involves thereception of a transmitted signal(s) at multiple geographicallyseparated reception points.

CoMP transmission and reception is being considered for inclusion innext generation wireless communications systems, such as in ThirdGeneration Partnership Project (3GPP) Long Term Evolution (LTE) Advancedstandards compliant communications systems, as a tool to improve thecoverage of high data rates, cell-edge throughput, and/or to increaseoverall communications system throughput in both high load and low loadscenarios.

Generally, a handover (HO), which is also commonly referred to as ahandoff, occurs when a user equipment changes from being served by afirst communications point to being served by a second communicationspoint.

SUMMARY OF THE INVENTION

Example embodiments of the present invention which provide a system andmethod for primary point handovers.

In accordance with an example embodiment of the present invention, amethod for operating a multiple point (MP) controller is provided. Themethod including receiving, from a source primary point, a handoverrequired message for a user equipment coupled to the source primarypoint, the handover required message including target primary pointinformation and MP radio bearer information for an MP radio bearer. Themethod also includes determining an MP configuration according to thehandover required message, and sending, to a target primary point, ahandover request message including the MP configuration and the MP radiobearer information. The method further includes sending, to the sourceprimary point, a handover message including the MP configuration, the MPradio bearer information, and reconfiguration information for the userequipment, the handover message initiating a handover of a subset of theMP radio bearer from the source primary point to the target primarypoint, and receiving, from the target primary point, a handover completemessage indicating completion of the handover.

In accordance with the above example embodiment, the handover requiredmessage may include non-MP radio bearer information for a non-MP radiobearer. The determining of the MP configuration may include removing thenon-MP radio bearer from the source primary point, and adding the non-MPradio bearer at the target primary point. The handover complete messagemay include an update to the MP radio bearer information.

In accordance with another example embodiment of the present invention,a method for operating a source primary point is provided. The methodincludes determining that a condition for a handover for a userequipment coupled to the source primary point is met, and sending ahandover required message for the user equipment, the handover requiredmessage including target primary point information and MP radio bearerinformation for an MP radio bearer. The method also includes receiving ahandover message including a MP configuration, the MP bearerinformation, and reconfiguration information for the user equipment, thehandover message initiating a handover of a subset of the MP radiobearer from the source primary point to a target primary point. Themethod further includes sending, to the user equipment, thereconfiguration information for the user equipment, sending, to thetarget primary point, status information for a transfer of the MP radiobearer, and receiving, from the target primary point, a handovercomplete message.

In accordance with another example embodiment of the present invention,a method for operating a target primary point is provided. The methodincludes receiving a handover request message for a user equipmentcoupled to a source primary point, the handover request messageincluding a multiple point (MP) configuration and MP radio bearerinformation for an MP radio bearer. The method also includes reserving aresource for a subset of the MP radio bearer, sending a handover requestresponse message including second MP radio bearer information for thesubset of the MP radio bearer. The method further includes transferringthe subset of the MP radio bearer from the source primary point,receiving, from the user equipment, a reconfiguration complete message,and sending, to the source primary point, a handover complete message.

In accordance with another example embodiment of the present invention,a multiple point (MP) controller is provided. The MP controller includesa receiver, a processor operatively coupled to the receiver, and atransmitter operatively coupled to the processor and to the receiver.The receiver receives, from a source primary point, a handover requiredmessage for a user equipment coupled to the source primary point, thehandover required message including target primary point information andMP radio bearer information for an MP radio bearer, and receives, from atarget primary point, a handover complete message indicating completionof a handover. The processor determines an MP configuration according tothe handover required message. The transmitter sends, to the targetprimary point, a handover request message including the MP configurationand the MP radio bearer information, and sends, to the source primarypoint, a handover message including the MP configuration, the MP radiobearer information, and reconfiguration information for the userequipment, the handover message initiating a handover of a subset of theMP radio bearer from the source primary point to the target primarypoint.

In accordance with the above example embodiment, the handover requiredmessage may include non-MP radio bearer information for a non-MP radiobearer. The processor may be configured to remove the non-MP radiobearer from the source primary point, and add the non-MP radio bearer atthe target primary point. The handover complete message may include anupdate to the MP radio bearer information.

In accordance with another example embodiment of the present invention,a source primary point is provided. The source primary point includes aprocessor, a transmitter operatively coupled to the processor, and areceiver operatively coupled to the processor. The processor determinesthat a condition for a handover for a user equipment coupled to thesource primary point is met. The transmitter sends a handover requiredmessage for the user equipment, the handover required message includingtarget primary point information and multiple point (MP) radio bearerinformation for an MP radio bearer, and sends, to the user equipment,reconfiguration information for the user equipment. The transmittersends, to the target primary point, status information for a transfer ofthe MP radio bearer. The receiver receives a handover message includinga MP configuration, the MP bearer information, and the reconfigurationinformation for the user equipment, the handover message initiating ahandover of a subset of the MP radio bearer from the source primarypoint to a target primary point, and receives, from the target primarypoint, a handover complete message.

One advantage of an embodiment is that radio bearer control techniques,as well as establishment, modification, and/or mobility techniques, in amultiple point environment are presented. Therefore, handovers in amultiple point environment are supported without having stringent timingrequirements on a backhaul between the communications points, whichsimplify implementation.

A further advantage of an embodiment is that techniques for handovers ina multiple point environment without requiring significant hardware,which helps to keep costs low.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawing, in which:

FIG. 1 illustrates an example communications system according to exampleembodiments described herein;

FIG. 2 illustrates an example communications system, wherein a transportof packets is highlighted according to example embodiments describedherein;

FIG. 3 illustrates an example portion of a protocol stack used in datatransmission over a radio bearer according to example embodimentsdescribed herein;

FIG. 4 illustrates an example communications system, wherein DL multiplepoint transmission (e.g., CoMP transmission) is taking place for some ofthe UEs operating in a coverage area of communications system accordingto example embodiments described herein;

FIG. 5 illustrates an example logical view of a communications system,highlighting a CoMP cooperating set and a CoMP controller according toexample embodiments described herein;

FIG. 6 illustrates an example message exchange occurring in a multiplepoint HO where there is a change in primary point (PP) of a multiplepoint operating set associated with the UE according to exampleembodiments described herein;

FIG. 7 illustrates an example flow diagram of operations in a multiplepoint controller as the multiple point controller participates in amultiple point HO according to example embodiments described herein;

FIG. 8 illustrates an example flow diagram of operations in a source PPas the source PP participates in a multiple point HO according toexample embodiments described herein;

FIG. 9 illustrates an example flow diagram of operation in a target PPas the target PP participates in a multiple point HO according toexample embodiments described herein;

FIG. 10 illustrates an example flow diagram of operations in a UE as theUE participates in a multiple point HO according to example embodimentsdescribed herein;

FIG. 11 illustrates an example flow diagram of operations in a MME asthe MME participates in a multiple point HO according to exampleembodiments described herein;

FIG. 12 illustrates an example flow diagram of operations in a servinggateway as the serving gateway participates in a multiple point HOaccording to example embodiments described herein;

FIG. 13 illustrates an example first communications device according toexample embodiments described herein; and

FIG. 14 illustrates an example second communications device according toexample embodiments described herein.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The operating of the current example embodiments and the structurethereof are discussed in detail below. It should be appreciated,however, that the present invention provides many applicable inventiveconcepts that can be embodied in a wide variety of specific contexts.The specific embodiments discussed are merely illustrative of specificstructures of the invention and ways to operate the invention, and donot limit the scope of the invention.

One embodiment of the invention relates to primary point (PP) handoversin a multiple point environment. For example, a multiple pointcontroller, upon receiving a handoff (HO) required message from a sourcePP, determines changes in a multiple point configuration that is theresult of the HO. Changes to the multiple point configurationinclude: 1) deciding which multiple point radio bearers will remain withthe source PP and which will transfer to the target PP with potentialmodifications to the multiple point radio bearers, and updating themultiple point configuration; and 2) transferring non-multiple pointradio bearers to a target PP. Furthermore, through the collaborationsamong multiple point controller, source and target primary points, andsecondary points, the example embodiments also try to 3) ensure thatin-order delivery of information is maintained, 4) ensure that Qualityof Service (QoS) levels for applications is maintained, as well as 5)generate security information for the target PPs and for secondarypoint(s) during the change of primary points.

The present invention will be described with respect to exampleembodiments in a specific context, namely a 3GPP LTE-Advanced compliantcommunications system. The invention may also be applied, however, toother standards compliant communications systems, such as IEEE 802.16m,WiMAX, and so on, as well as non-standards compliant communicationssystems that support multiple point transmission.

FIG. 1 illustrates a communications system 100. Communications system100 includes UE 110 and UE 112 wirelessly accessing services through anEnhanced Universal Mobile Telecommunications System (UMTS) TerrestrialRadio Access Network (E-UTRAN) 105. E-UTRAN 105 includes one or moreevolved NodeBs (eNB) that serve the UEs coupled to E-UTRAN 105. TheeNB(s) in E-UTRAN provides an air interface for communications system100. A connection may be setup from a UE through E-UTRAN 105, a servinggateway (serving GW) 115, and a packet data network gateway (PDN GW) 120to an operator's Internet Protocol (IP) services network 125.

While it is understood that communications systems may employ multipleeNBs capable of communicating with a number of UEs, only one E-UTRAN,two UEs, one serving GW, and one PDN GW are illustrated for simplicity.

Communications system 100 also includes a Mobility Management Entity(MME) 130 that manages UE mobility, such as bearer management services,HOs, and the like. Also, a Serving General Packet Radio Service (GPRS)Support Node (SGSN) 135 is responsible for the delivery of data to andfrom UEs over a UMTS radio system, a Home Subscriber Server (HSS) 140 isresponsible for maintaining subscription related information for UEs,and a Policy Control and Charging Rules Function (PCRF) 145 isresponsible for determining policy rules in communications system 100.

FIG. 2 illustrates a communications system 200, wherein a transport ofpackets is highlighted. The transport of packets from PDN GW 220 to UE205 may be organized through Evolved Packet System (EPS) bearers, whichmay be radio or wireline bearers. Between PDN GW 220 and serving GW 215,an S5/S8 bearer supports the transport of packets, while between servingGW 215 and eNB 210, an S1 bearer supports the transport of packets. Aradio bearer supports the transport of packets between eNB 210 and UE205. Traffic flows may be aggregated and then sent over respectivebearers to their intended destination.

FIG. 3 illustrates a portion of a protocol stack 300 used in datatransmission over a radio bearer. Protocol stack 300 illustrates amedium access control (MAC) layer 305, a radio link control (RLC) layer310, and a packet data convergence control (PDCP) layer 315. In currentgeneration 3GPP LTE communications systems (e.g., 3GPP LTE Release-8,Release-9, and Release-10), each radio bearer of a UE is associated withone PDCP entity, and each PDCP entity is associated with one RLC entityfor DL transmissions.

FIG. 4 illustrates a communications system 400, wherein DL multiplepoint transmission (e.g., CoMP transmission) is taking place for some ofthe UEs operating in a coverage area of communications system 400.Although the discussion of FIG. 4 focuses on eNBs as communicationscontrollers, other types of communications controllers may be used inplace of or in conjunction with eNBs. For example, BSs, Low Power Nodes(LPN), femto cells, pico cells, and so on, may be used as replacementsof or in conjunction with eNBs. Therefore, the discussion of eNBs shouldnot be construed as being limiting to either the scope or the spirit ofthe example embodiments.

Furthermore, the discussion presented herein focuses on CoMPtransmission. However, the example embodiments presented here are alsooperable with a more general form of CoMP transmission, i.e., multiplepoint transmission. Therefore, the discussion of CoMP transmissionshould not be construed as being limiting to either the scope or thespirit of the example embodiments.

Communications system 400 includes a number of eNBs, such as eNB 405,eNB 407, and eNB 409, and a number of remote radio heads (RRH), such asRRH 410, RRH 412, RRH 414, RRH 416, RRH 418, and RRH 420. RRHs may alsobe referred to as remote radio units (RRU). Communications system 400also includes a number of UEs, such as UE 425, UE 427, and UE 429. TheUEs may be served by one or more eNBs, one or more RRHs, or acombination of eNBs and RRHs. The eNBs may allocate a portion of theirbandwidth to the RRHs in order to help improve coverage, performance,and so forth.

As shown in FIG. 4, UE 425 may be served by RRH 410 and RRH 412, as wellas eNB 405. While UE 427 may be served by RRH 414, RRH 416, and RRH 418.UE 429 may be served by RRHs controlled by different eNBs, such as RRH414 and RRH 418 (controlled by eNB 409) and RRH 420 (controlled by eNB407).

A communications point within a DL serving set may be referred to as aprimary communications point (or simply primary or primary point) andthe remaining communications point(s) in the DL serving set may bereferred to as secondary communications point(s) (or simply secondary,secondary point, secondaries, or secondary points). The primarycommunications point may be considered to be a controllingcommunications point, responsible for assigning identificationinformation, distributing DL data to the secondary communicationspoints, and so forth.

Communications points, such as eNBs, cells of eNBs, RRHs, and so forth,involved in a multiple point operation form a multiple point cooperatingset. Furthermore, when the communications points are involved in CoMPoperation, the communications points form a CoMP cooperating set. Thecommunications points may be associated with a single cell or differentcells. A network pre-connected, UE assisted approach can be taken toconfigure a CoMP cooperating set for a UE. Based on the condition ofchannels between a UE and a set of communications points, which arepre-connected to allow inter-communications point communications, a CoMPcooperating set may be dynamically setup for an application's databearer to include communications points with congenial channelcharacteristics.

Among members of a CoMP cooperating set, the primary communicationspoint may be responsible for UE specific signaling, including paging.Other members of the CoMP cooperating set may contribute to datacommunications.

Communications system 400 also includes a controller 440 that maycontrol multiple point operations in one or more multiple pointcooperating sets. As an example, controller 440 may determine multiplepoint configurations, changes to multiple point cooperating sets,initiate handovers, and the like. There may be a single globalcontroller or multiple localized controllers. The global controller maycontrol multiple point operations in an entire communications system,while localized controllers may control multiple point operations in alocal region, which may include one or more multiple point cooperatingsets. According to an alternative embodiment, a point within a multiplepoint cooperating set may serve as a controller for the multiple pointcooperating set.

FIG. 5 illustrates a logical view of a communications system 500,highlighting a CoMP cooperating set and a CoMP controller. As shown inFIG. 5, a CoMP controller 505 may be viewed as a centralized controlpoint with a CoMP cooperating set 510. CoMP controller 505 may provide aunified control for setting up, configuring CoMP communications forradio bearers, coordinating the operation of multiple communicationspoints within CoMP cooperating set 510, and so on. CoMP controller 505may be realized as a separate physical entity connecting all (existingas well as potential) communications points of CoMP cooperating set 510.Alternatively, CoMP controller 505 may be a logical function co-locatedwithin an existing network entity, such as an eNB.

Communications system 500 also includes a MME pool 515 that may beresponsible for providing MMEs that may be used for radio beareractivation and/or deactivation, as well as UE tracking and pagingprocedures. MME pool 515 may include a number of MMEs that may beassigned to assist a CoMP controller (such as CoMP controller 505) whenthe CoMP controller has a need for radio bearer management, and so on.Assigned MMEs may be released once they are no longer needed or anotherone becomes better suited to the purpose.

Communications system 500 also includes a serving gateway (S-GW) pool520 that may be responsible for providing S-GWs that may be used aspoint of entry and/or exit for traffic to or from a UE. S-GW pool 520may include a number of S-GWs that may be assigned when needed andreleased when no longer needed or another one becomes better suited tothe purpose.

As discussed previously, in a standard cellular HO, a radio bearer(s)associated with a UE at a source communications point is transferred toa target communications point and the UE continues to receiveinformation from the target communications point and to transmitinformation to the target communications point.

However, in a multiple point environment, where a UE may transmit to orreceive transmissions from multiple communications points, severaldifferent forms of multiple point HOs may take place. In a first form ofmultiple point HO, no change in the PP occurs. However, radio bearersinvolved in multiple point operation are transferred from a first SP toa second SP. In a second form of multiple point HO, there is a change inthe PP associated with the UE. When there is a change in the PPassociated with the UE, it may be necessary to move signaling radiobearers and non-multiple point radio bearers from a source PP to atarget PP, as well as a subset of multiple point radio bearers to thetarget PP from the source PP, while potentially retaining a remainder ofthe multiple point radio bearers at the source PP (potentially withmodification to their Radio Resource Management and/or Quality ofService (RRM/QoS) parameters. Furthermore, an updated multiple point(MP) configuration, and a configuration of radio bearers on the sourcePP and the target PP may be determined based on channel conditionreports. QoS levels for an application (e.g., aggregated over radiobearers for communications points involved in the multiple pointoperation) are also maintained during the multiple point HO.

FIG. 6 illustrates a message exchange 600 occurring in a multiple pointHO where there is a change in PP of a multiple point operating setassociated with the UE. Message exchange 600 highlights messagesexchanged between a UE 605, a source PP 607, a secondary point 609, atarget PP 611, a multiple point controller 613, a MME 615, and a servinggateway 617, in performing a multiple point HO where there is a changein PP of a multiple point operating set associated with the UE.

Although the discussion presented herein focuses on the entitiesinvolved in the multiple point HO (e.g., UE 605, source PP 607,secondary point 609, target PP 611, multiple point controller 613, MME615, and serving gateway 617) as separate entities, some of the entitiesmay be implemented as logical entities located at a physical entity. Asan example, multiple point controller 613 may be implemented as alogical entity and implemented in source PP 607, target PP 611, or MME615.

UE 605 may send a measurement report to source PP 607 (shown as event620). According to an example embodiment, the measurement report is inthe form of a Reference Signal Received Power (RSRP) report or aReference Signal Received Quality (RSRQ) report. The measurement may beperformed at UE using cell reference signals (CRS) or channel stateinformation reference signals (CSI-RS). UE 605 may be configured toperiodically or at specific times send a measurement report to source PP607. UE 605 may alternatively be configured to send a measurement reportto source PP 607 upon an occurrence of an event, such as a reception ofa measurement report request, a metric (such as an error rate, a datarate, a cell's signal strength, the difference between two cells' signalstrengths, and the like) meeting a specified threshold, a cell's signalstrength becomes better than a first threshold and another cell's signalstrength becomes lower than a second threshold, and the like. Source PP607 may also forward the measurement report from UE 605 to multiplepoint controller 613.

Based on the measurement report, source PP 607 may send a first messageincluding a HO required indicator to multiple point controller 613(shown as event 622). As an example, source PP 607 may determine if a HOis required by comparing information contained in the measurement reportwith one or more conditions and if one or more conditions is met, sourcePP 607 determines that the HO is required. The conditions include asignal strength measurement of source PP 607 meeting a signal threshold,a signal strength measurement of target PP 611 exceeding a signalstrength measurement of source PP 607, signal strength measurement ofseveral target PPs exceeding a signal strength measurement of source PP607, and the like. According to an example embodiment, the first messageincludes identity information of target PP 611 and its security keyinformation, including but not limited to {eNB key (K_(eNB*)), Next hopChaining Counter (NCC)}. The first message also includes identifyinginformation for radio bearers to be handed over to target PP 611.

Although the discussion focuses on source PP 607 initiating the multiplepoint HO by transmitting the first message including the HO requiredindicator to multiple point controller 613, other network entities mayinitiate the multiple point HO. As an example, a centralized networkentity or a locally centralized network entity having access to themeasurement reports from UE 605 as well as neighbor information ofsource PP 607 can initiate the multiple point HO by transmitting amessage including the HO required indicator to multiple point controller613. In such a situation, the message from the centralized networkentity may need to specify identity information about source PP 607, aswell as target PP 611 and other information contained in the firstmessage.

Multiple point controller 613, upon receiving the first message with theHO required indicator, may determine a change in the multiple pointconfiguration using the information provided by source PP 607. Changesto the multiple point configuration include changes to radio bearersused in multiple point operation at source PP 607 once the multiplepoint HO completes, changes to radio bearers used in multiple pointoperation at target PP 611 once the multiple point HO completes, changesto radio bearers not used in multiple point operation at source PP 607and at target PP 611 once the multiple point HO completes, changes toparameters of the radio bearers, changes to security key information,and the like.

Multiple point controller 613 may begin HO preparation at target PP 611by sending a second message including a handover request indication(shown as event 624). According to an example embodiment, the secondmessage includes identifying information of signaling and data radiobearers that are to be transferred from source PP 607 to target PP 611,data radio bearers in multiple point operation and associated secondarypoints along with their RRM/QoS parameters (which may include a statusof a multiple point transmission mode, e.g., if a radio bearer split isenacted with other secondary points), and the like. The second messagealso includes security information, such as {eNB key (K_(eNB*)), Nexthop Chaining Counter (NCC)}, for target PP 611 for use after completionof the multiple point HO.

Target PP 611 may reserve resources for radio bearers according toinformation in the second message from multiple point controller 613.Target PP 611 also responds to the second message by sending a thirdmessage including a HO request acknowledgement (shown as event 626).According to an example embodiment, the third message includes identityinformation assigned to UE 605 in target PP 611, as well as receivedsecurity key information, e.g., NCC. Additionally, for each secondarypoint independently supporting a data radio bearer for UE 605, target PP611 may update its security key information, e.g., {K_(eNB*), NCC}, forthe respective secondary point and include an updated NCC in the thirdmessage. Furthermore, if source PP 607 becomes a secondary point aftercompletion of the multiple point HO and independently supports a dataradio bearer, target PP 611 may generate security key information, e.g.,{K_(eNB*), NCC}, for source PP 607 to use after completion of themultiple point HO.

The security key information, e.g., {K_(eNB*), NCC}, of the secondarypoints (potentially including a secondary point that was source PP 607prior to completion of the multiple point HO) may be selecteddifferently from security key information of target PP 611. As anexample, the security key information of the secondary points may berelated to the security key information of target PP 611. Additionally,target PP 611 may choose not to change the security key informationalready assigned to some or all of the secondary points.

Multiple point controller 613 may send a fourth message including a HOcommand indicator to source PP 607 (shown as event 628). According to anexample embodiment, the fourth message (with the HO command indicator)is used to instruct source PP 607 to perform a primary point HO andincludes identification information regarding signaling and data radiobearers to be transferred to target PP 611, as well as radio bearersthat are to remain with source PP 607 once the multiple point HOcompletes. The identification information also includes associatedparameters, such as RRM/QoS parameters, for the radio bearers for use inmultiple point operation.

Additionally, the fourth message includes information for UE 605.According to an example embodiment, the information for UE 605 iscontained in a signaling container and includes information regardingthe identity assigned to UE 605 in target PP 611, security keyinformation to be used in target PP 611 and the secondary points aftercompletion of the multiple point HO, information about signaling anddata radio bearers to be transferred from source PP 607 to target PP611, information about data radio bearers at source PP 607 and target PP611 that will continue in multiple point operations, as well asparameters, such as RRM/QoS parameters, of the radio bearers.

Source PP 607 may send a fifth message including a Radio ResourceControl (RRC) connection reconfiguration indicator to UE 605 toreconfigure the UE and to start the primary point HO (shown as event630). According to an example embodiment, the fifth message passes theinformation for UE 605 (e.g., the signaling container) to UE 605.

Source PP 607 may send a sixth message including a radio bearer statustransfer message to target PP 611 to convey the status of radio bearersin multiple point operation (shown as event 632). According to anexample embodiment, for radio bearers that are split over multiplecommunications points, their downlink PDCP sequence number transmitterstatus and logical channel identities associated with involved RLCentities at transmission points are passed to target PP 611. Thedownlink PDCP sequence number transmitter status provides information toderive a subsequent PDCP sequence number that target PP 611 assigns tonew service data units (SDU) not already having been assigned a PDCPsequence number. According to an example embodiment, for radio bearerssupported on other secondary points, their identities and associatedlogical channel identities are passed to target PP 611. Source PP 607forwards to target PP 611 PDCP protocol data units (PDU) whose deliveryhas not been confirmed. The forwarding of SDUs and PDUs by source PP 607to target PP 611 are shown collectively as event 634.

UE 605, utilizing the information from source PP 607 contained in thefifth message, may determine that data packets of UE specific signalingand data radio bearers not participating in multiple point operation areto be sent from target PP 611. UE 605 may also obtain updatedparameters, such as RRM/QoS parameters for data radio bearers inmultiple point operation. After preparing to receive transmissions fromtarget PP 611, as well as from multiple points in multiple pointoperation, and updating its security key information, UE 605 connects totarget PP 611 and sends a seventh message including a RRC connectionreconfiguration complete indicator to target PP 611 (shown as event636).

Target PP 611, upon receiving the seventh message from UE 605, may sendan eighth message including a HO complete indicator to multiple pointcontroller 613 (shown as event 638). According to an example embodiment,for each secondary point independently supporting a data radio bearer,target PP 611 includes updated security key information, e.g.,{K_(eNB*), NCC}, if any in the eighth message.

Target PP 611 may also send a ninth message including a path switchrequest indicator to MME 615 (shown as event 640). According to anexample embodiment, the path switch request indicator informs MME 615that there has been a change in PP. Furthermore, the ninth messageincludes information about enumerated evolved packet system (EPS)bearers whose packets should be sent to target PP 611 from now on. Theinformation about the enumerated EPS bearers may be in the form of alist.

Multiple point controller 613 may send a tenth message including amultiple point radio bearer configuration request indication to thesecondary point(s) to inform them of completion of the multiple point HO(shown as event 642). According to an example embodiment, the tenthmessage also includes updates of parameters, such as RRM/QoS parametersfor data radio bearers in multiple point operation on the secondarypoint(s). For secondary point(s) independently supporting a data radiobearer, the tenth message also include updated security key information,e.g., {K_(eNB*), NCC}, if available. Also, for secondary point(s)independently supporting a data radio bearer, if updated security keyinformation is provided in the tenth message, the updated securityinformation should be utilized. For radio bearers that are split overmultiple points, secondary point(s) may stop transmission of PDCP PDUsreceived from source PP 607.

The secondary point(s) may send an eleventh message including a radiobearer status transfer indicator to target PP 611 to convey the statusof radio bearers used in multiple point operation (shown as event 644).While, for radio bearers that are split over multiple points, theirdownlink PDCP sequence number transmitter status indicates the sequencenumber of PDCP PDUs whose delivery has been confirmed on a secondarypoint.

MME 615 may send a twelfth message including a user plane update requestindicator to serving gateway 617 (shown as event 646). According to anexample embodiment, the twelfth message includes an address of target PP611, as well as a list of the enumerated EPS bearers whose packetsshould be sent to target PP 611 from now on.

Serving gateway 617 may send a thirteenth message including a user planeupdate response indicator to MME 615 (shown as event 648). Servinggateway 617 may also start to send data packets of the enumerated EPSbearers to target PP 611 using the received address (from the twelfthmessage), shown collectively as event 654 (for radio bearers not inmultiple point operation) and event 656 (for radio bearers in multiplepoint operation).

MME 615 may confirm the path switch with target PP 611 by sending afourteenth message including a path switch request acknowledgement(shown as event 650). Target PP 611 may send a fifteenth messageincluding a HO complete indicator to source PP 607 (shown as event 652).According to an example embodiment, source PP 607 may release resourcespreviously reserved for radio bearers (both signaling and data radiobearers) that have been moved to target PP 611 after receipt of thefifteenth message. Target PP 611 may send downlink data directly to UE605 (shown as event 658) or split the downlink data to the secondarypoint(s) (shown as event 660). The secondary point(s) also send thedownlink data to UE 605 (shown as event 662).

In general, packets associated with signaling and/or data radio bearersnot in multiple point operation may be sent to target PP 611 fordelivery, while packets associated with data radio bearers in multiplepoint operation are sent to multiple point controller 613 fordistribution according to the multiple point configuration. In asituation with data radio bearers supported on a secondary point(s),multiple point controller 613 forwards associated data to correspondingsecondary point(s). In a situation with data radio bearers that aresplit over multiple geographically separated communications points,multiple point controller 613 passes associated data to target PP 611which then distributes the data through a data splitting interfacebetween a single PDCP entity and multiple RLC entities. Target PP 611and the secondary point(s) send the data to UE 605.

According to an example embodiment, the various messages described abovein the discussion of FIG. 6 may be transmitted on their own or incombination with one or more other messages, e.g., the various messagesmay be embedded in other messages. Additionally, some of the messagesmay be transmitted in a different order than what is illustrated anddiscussed without changing the spirit or the scope of the exampleembodiments.

FIG. 7 illustrates a flow diagram of operations 700 in a multiple pointcontroller as the multiple point controller participates in a multiplepoint HO. Operations 700 may be indicative of operations taking place ina multiple point controller, such as controller 440 of FIG. 4, as themultiple point controller participates in a multiple point HO from asource PP to a target PP.

Operations 700 may begin with the multiple point controller receiving ameasurement report(s) from the source PP (block 705). The measurementreport(s) may be from UE served by the source PP and may be in the formof a RSRP report(s), RSRQ report(s), and the like. The multiple pointcontroller may also receive a first message with a HO required indicatorfor a UE (block 710). According to an example embodiment, the firstmessage may be sent by the source PP or by a network entity that caninitiate HOs. The first message includes identity information of thetarget PP and its security key information, including but not limited to{eNB key (K_(eNB*)), Next hop Chaining Counter (NCC)}. The first messagealso includes identifying information for radio bearers to be handedover to target PP.

Based on the information in the first message, multiple point controllermay determine a change in the multiple point configuration (block 715).Changes to the multiple point configuration include changes to radiobearers used in multiple point operation at source PP 607 and at targetPP 611 once the multiple point HO completes, changes to radio bearersused in multiple point operation at secondary points, changes toparameters of the radio bearers, and the like.

The multiple point controller may send a second message including ahandover request indication to the target PP (block 720). According toan example embodiment, the second message includes identifyinginformation of signaling and data radio bearers that are to betransferred from the source PP to the target PP, data radio bearers inmultiple point operation and associated secondary points along withtheir RRM/QoS parameters (which may include a status of a multiple pointtransmission mode, e.g., if a radio bearer split is enacted with othersecondary points), and the like. The second message also includessecurity information for the target PP to use after completion of themultiple point HO.

The multiple point controller may receive a third message including a HOrequest acknowledgement from the target PP (block 725). According to anexample embodiment, the third message includes identity informationassigned to the UE in the target PP, as well as received security keyinformation, e.g., NCC. Additionally, for each secondary pointindependently supporting a data radio bearer for the UE, the target PPmay update its security key information for the respective secondarypoint and include an updated NCC in the third message. Furthermore, ifthe source PP becomes a secondary point after completion of the multiplepoint HO and independently supports a data radio bearer, the target PPmay generate security key information for the source PP to use aftercompletion of the multiple point HO.

The multiple point controller may initiate the multiple point HO bysending a fourth message including a HO command indicator to the sourcePP (block 730). According to an example embodiment, the fourth message(with the HO command indicator) is used to instruct the source PP toperform a primary point HO and includes identification informationregarding signaling and data radio bearers to be transferred to thetarget PP, as well as radio bearers that are to remain with the sourcePP once the multiple point HO completes. The identification informationalso includes associated parameters, such as RRM/QoS parameters, for theradio bearers for use in multiple point operation. Additionally, thefourth message includes information for the UE, which may include butare not limited to: instructions about the identity assigned to UE inthe target PP, the NCCs to be used after handover in the target PP andsecondary points, signaling and data radio bearers to be transferredfrom the source PP to the target PP, a list of data radio bearers on thesource PP and the target PP to continue the multiple point operation,respective RRM/QoS parameters of the signaling and data radio bearers,and the like.

The multiple point controller may receive a fifth message including a HOcomplete indicator from the target PP to indicate that the multiplepoint HO is complete (block 735). The multiple point controller may senda sixth message including a multiple point radio bearer configurationrequest indication to the secondary point(s) to inform them ofcompletion of the multiple point HO (block 740). According to an exampleembodiment, the sixth message also includes updates of parameters, suchas RRM/QoS parameters for data radio bearers in multiple point operationon the secondary point(s). For secondary point(s) independentlysupporting a data radio bearer, the sixth message also include updatedsecurity key information if available. Also, for secondary point(s)independently supporting a data radio bearer, if updated security keyinformation is provided in the sixth message, the updated securityinformation should be utilized. For radio bearers that are split overmultiple points, secondary point(s) may stop transmission of PDCP PDUsreceived from the source PP.

FIG. 8 illustrates a flow diagram of operations 800 in a source PP asthe source PP participates in a multiple point HO. Operations 800 may beindicative of operations taking place in a source PP, such as an eNB, aRRH, and the like, as the source PP participates in a multiple point HOfrom the source PP to a target PP.

Operations 800 may begin with the source PP receiving a measurementreport(s) from a UE (block 805). The measurement report(s) may be fromUE served by the source PP and may be in the form of a RSRP report(s),RSRQ report(s), and the like. The source PP may forward the measurementreport(s) to a multiple point controller (block 810).

The source PP, based on information in the measurement report(s), maydetermine that a multiple point HO is needed and send a first messageincluding a HO required indicator to the multiple point controller(block 815). According to an example embodiment, the first messageincludes identity information of the target PP and its security keyinformation, including but not limited to {K_(eNB*), NCC}. The firstmessage also includes identifying information for radio bearers to behanded over to the target PP.

The source PP may receive a second message including a second messageincluding a HO command indicator from the multiple point controller(block 820). According to an example embodiment, the second message(with the HO command indicator) instructs the source PP to perform aprimary point HO and includes identification information regardingsignaling and data radio bearers to be transferred to the target PP, aswell as radio bearers that are to remain with the source PP once themultiple point HO completes. The identification information alsoincludes associated parameters, such as RRM/QoS parameters, for theradio bearers for use in multiple point operation.

Additionally, the second message includes information for the UE.According to an example embodiment, the information for the UE iscontained in a signaling container and includes information regardingthe identity assigned to the UE in the target PP, security keyinformation to be used in the target PP and the secondary points aftercompletion of the multiple point HO, information about signaling anddata radio bearers to be transferred from the source PP to the targetPP, information about data radio bearers at the source PP and the targetPP that will continue in multiple point operations, as well asparameters, such as RRM/QoS parameters, of the radio bearers.

The source PP may reconfigure the UE and start the primary HO (block825). According to an example embodiment, the target PP may reconfigurethe UE and start the primary HO by sending a third message including aRadio Resource Control (RRC) connection reconfiguration indicator to theUE. The third message passes the information for the UE from the secondmessage to the UE.

The source PP may provide radio bearer status to the target PP bysending a fourth message including a radio bearer status transfermessage to the target PP to convey the status of radio bearers inmultiple point operation (block 830). According to an exampleembodiment, for radio bearers that are split over multiplecommunications points, their downlink PDCP sequence number transmitterstatus and logical channel identities associated with involved RLCentities at communications points are passed to the target PP. Thedownlink PDCP sequence number transmitter status provides information toderive a subsequent PDCP sequence number that the target PP assigns tonew SDUs not already having been assigned a PDCP sequence number.According to an example embodiment, for radio bearers supported on othersecondary points, their identities and associated logical channelidentities are passed to the target PP. The source PP forwards to thetarget PP the PDCP PDUs whose delivery has not been confirmed. Theforwarding of SDUs and PDUs by the source PP to the target PP are showncollectively as block 835.

The source PP, now operating as a secondary point, may receive a fifthmessage including a multiple point radio bearer configuration requestindication from the multiple point controller that informs the source PP(as well as other secondary points) that the multiple point HO iscomplete (block 840). According to an example embodiment, the fifthmessage also includes updates of parameters, such as RRM/QoS parametersfor data radio bearers in multiple point operation on the secondarypoint(s). For secondary point(s) independently supporting a data radiobearer, the fifth message also include updated security key informationif available. Also, for secondary point(s) independently supporting adata radio bearer, if updated security key information is provided inthe fifth message, the updated security information should be utilized.For radio bearers that are split over multiple points, secondarypoint(s) may stop transmission of PDCP PDUs received from the source PP.

The source PP may send a sixth message including a radio bearer statustransfer indicator to the target PP to convey the status of radiobearers used in multiple point operation (block 845). The source PP mayreceive a seventh message including a HO complete indicator to thesource PP to inform the source PP that the multiple point HO is complete(block 850) and the source PP may release resources previously reservedfor radio bearers (both signaling and data radio bearers) that have beenmoved to the target PP (block 855).

FIG. 9 illustrates a flow diagram of operation 900 in a target PP as thetarget PP participates in a multiple point HO. Operations 900 may beindicative of operations taking place in a target PP, such as an eNB, aRRH, and the like, as the target PP participates in a multiple point HOfrom a source PP to the target PP.

The target PP may receive a first message including a handover requestindication from the multiple point controller (block 905). According toan example embodiment, the first message includes identifyinginformation of signaling and data radio bearers that are to betransferred from the source PP to the target PP, data radio bearers inmultiple point operation and associated secondary points along withtheir RRM/QoS parameters (which may include a status of a multiple pointtransmission mode, e.g., if a radio bearer split is enacted with othersecondary points), and the like. The first message also includessecurity information for the target PP to use after completion of themultiple point HO.

The target PP may reserve resources for radio bearers according toinformation in the first message (block 910). The target PP 611 mayrespond to the first message by sending a second message including a HOrequest acknowledgement to the multiple point controller (block 915).According to an example embodiment, the second message includes identityinformation assigned to the UE in the target PP, as well as receivedsecurity key information, e.g., NCC. Additionally, for each secondarypoint independently supporting a data radio bearer for the UE, thetarget PP may update its security key information and include an updatedNCC in the second message. Furthermore, if the source PP becomes asecondary point after completion of the multiple point HO andindependently supports a data radio bearer, the target PP may generatesecurity key information for the source PP to use after completion ofthe multiple point HO.

The target PP may receive a second message including a radio bearerstatus transfer message from the source PP (block 920). According to anexample embodiment, for radio bearers that are split over multiplecommunications points, their downlink PDCP sequence number transmitterstatus and logical channel identities associated with involved RLCentities at transmission points are passed to the target PP. Thedownlink PDCP sequence number transmitter status provides information toderive a subsequent PDCP sequence number that the target PP assigns tonew SDU not already having been assigned a PDCP sequence number.According to an example embodiment, for radio bearers supported on othersecondary points, their identities and associated logical channelidentities are passed to the target PP. The target PP also receives fromthe source PP PDCP PDU whose delivery has not been confirmed. Thereceipt of SDUs and PDUs from the source PP at the target PP is shown asblock 925.

The target PP may also send a third message including a path switchrequest indicator to a MME (block 930). According to an exampleembodiment, the path switch request indicator informs the MME that therehas been a change in PP. Furthermore, the third message includesinformation about enumerated evolved packet system (EPS) bearers whosepackets should be sent to the target PP from now on. The informationabout the enumerated EPS bearers may be in the form of a list.

The target PP may receive a fourth message including a radio bearerstatus transfer indicator from the source PP (now operating as asecondary point) as well as from other secondary points (block 935).According to an example embodiment, the fourth message conveys thestatus of radio bearers used in multiple point operation. While, forradio bearers that are split over multiple points, their downlink PDCPsequence number transmitter status indicates the sequence number of PDCPPDUs whose delivery has been confirmed on a secondary point.

The target PP may receive a fifth message including a path switchrequest acknowledgement (block 940). The target PP may send a sixthmessage including a HO complete indicator to the source PP (block 945).

FIG. 10 illustrates a flow diagram of operations 1000 in a UE as the UEparticipates in a multiple point HO. Operations 1000 may be indicativeof operations taking place at a UE, such as UE 425, UE 429, and thelike, as the UE participates in a multiple point HO from a source PP toa target PP.

The UE may send a measurement report to the source PP (block 1005).According to an example embodiment, the measurement report may be in theform of a Reference Signal Received Power (RSRP) report, a RSRQ report,and the like. The measurement may be performed at UE on cell referencesymbols (CRS) or channel state information reference symbols (CSI-RS).The UE may be configured to periodically or at specific times send ameasurement report to the source PP. The UE may alternatively beconfigured to send a measurement report to the source PP upon anoccurrence of an event, such as a reception of a measurement reportrequest, a metric (such as an error rate, a data rate, a cell's signalstrength, the difference between two cells' signal strengths, and thelike) meeting a specified threshold, a cell's signal strength becomesbetter than a first threshold and another cell's signal strength becomeslower than a second threshold, and the like.

The UE may receive a first message including a Radio Resource Control(RRC) connection reconfiguration indicator from the source PP toreconfigure the UE and to start the primary point HO (block 1010).According to an example embodiment, the first message passes theinformation for the UE (e.g., the signaling container sent by themultiple point controller) to the UE, which may include but are notlimited to: instructions about the identity assigned to UE in the targetPP, the NCCs to be used after handover in the target PP and secondarypoints, signaling and data radio bearers to be transferred from thesource PP to the target PP, a list of data radio bearers on the sourcePP and the target PP to continue the multiple point operation,respective RRM/QoS parameters of the signaling and data radio bearers,and the like.

The UE may prepare for data reception from transmissions made by thetarget PP (block 1015). According to an example embodiment, the UE,utilizing the information sent by the multiple point controller, maydetermine that data packets of UE specific signaling and data radiobearers not participating in multiple point operation are to be sentfrom the target PP. The UE may also obtain updated parameters, such asRRM/QoS parameters for data radio bearers in multiple point operation.The UE may also connect to the target PP (block 1020) and respond to thefirst message by sending a second message including a RRC connectionreconfiguration complete indicator to the target PP (block 1030). The UEmay also begin to receive DL data (block 1035).

FIG. 11 illustrates a flow diagram of operations 1100 in a MME as theMME participates in a multiple point HO. Operations 1100 may beindicative of operations taking place at a MME as the MME participatesin a multiple point HO from a source PP to a target PP.

The MME may receive a first message including a path switch requestindicator from the target PP (block 1105). According to an exampleembodiment, the path switch request indicator informs the MME that therehas been a change in PP. Furthermore, the first message includesinformation about enumerated evolved packet system (EPS) bearers whosepackets should be sent to target PP 611 from now on. The informationabout the enumerated EPS bearers may be in the form of a list.

The MME may send a second message including a user plane update requestindicator to a serving gateway (block 1110). According to an exampleembodiment, the second message includes an address of the target PP, aswell as a list of the enumerated EPS bearers whose packets should besent to the target PP from now on.

The MME may receive a third message including a user plane updateresponse indicator from the serving gateway (block 1115). The MME mayconfirm the path switch with the target PP by sending a fourth messageincluding a path switch request acknowledgement to the target PP (block1120).

FIG. 12 illustrates a flow diagram of operations 1200 in a servinggateway as the serving gateway participates in a multiple point HO.Operations 1200 may be indicative of operations taking place at aserving gateway as the serving gateway participates in a multiple pointHO from a source PP to a target PP.

The serving gateway may receive a first message including a user planeupdate request indicator to a serving gateway (block 1205). According toan example embodiment, the first message includes an address of thetarget PP, as well as a list of the enumerated EPS bearers whose packetsshould be sent to the target PP from now on.

The serving gateway may start to send data packets of the enumerated EPSbearers to the target PP using the address received in the first message(block 1210). The serving gateway may also send a second messageincluding a user plane update response indicator to the MME (block1215).

FIG. 13 illustrates a first communications device 1300. Communicationsdevice 1300 may be an implementation of a multiple point controller.Communications device 1300 may be used to implement various ones of theembodiments discussed herein. As shown in FIG. 13, a transmitter 1305 isconfigured to send packets and a receiver 1310 is configured to receivepackets. Transmitter 1305 and receiver 1310 may have a wirelessinterface, a wireline interface, or a combination thereof.

A measurement report processing unit 1320 is configured to processmeasurement reports from UEs (or communications points). Measurementreport processing unit 1320 is also configured to solicit measurementreports from the UEs (or communications points). A HO processing unit1322 is configured to coordinate a multiple point HO between a source PPand a target PP. HO processing unit 1322 is configured to determinechanges in a multiple point configuration according to the resourcereport(s). HO processing unit 1322 is configured to initiate themultiple point HO.

A radio bearer processing unit 1324 is configured to make changes toradio bearers (including signaling and data radio bearers that aremultiple point and/or non multiple point radio bearers) impacted by themultiple point HO. Radio bearer processing unit 1324 is configured tomake changes to parameters, such as RRM/QoS parameters, of radiobearers. A memory 1330 is configured to store resource reports, multiplepoint configurations, radio bearer configurations and parameters, sourcePP and/or target PP information, radio bearer status, multiple point HOstatus, and the like.

The elements of communications device 1300 may be implemented asspecific hardware logic blocks. In an alternative, the elements ofcommunications device 1300 may be implemented as software executing in aprocessor, controller, application specific integrated circuit, and thelike. In yet another alternative, the elements of communications device1300 may be implemented as a combination of software and/or hardware.

As an example, transmitter 1305 and receiver 1310 may be implemented asa specific hardware block, while resource report processing unit 1320,HO processing unit 1322, and radio bearer processing unit 1324 may besoftware modules executing in a processor 1315, a microprocessor, acustom circuit, or a custom compiled logic array of a field programmablelogic array.

FIG. 14 illustrates a second communications device 1400. Communicationsdevice 1400 may be an implementation of a communications point, an eNB,a BS, a RRH, and the like. Communications device 1400 may be used toimplement various ones of the embodiments discussed herein. As shown inFIG. 14, a transmitter 1405 is configured to send packets and a receiver1410 is configured to receive packets. Transmitter 1405 and receiver1410 may have a wireless interface, a wireline interface, or acombination thereof.

A measurement report processing unit 1420 is configured to processmeasurement reports from UEs or communication points. Measurement reportprocessing unit 1420 is configured to solicit measurement reports fromUEs or communications points. A security information generating unit1422 is configured to generate security information for UEs,communications points, secondary points, and the like, communicatingwith communications device 1400.

A radio bearer processing unit 1424 is configured to make changes toradio bearers (including signaling and data radio bearers that aremultiple point and/or non multiple point radio bearers) impacted by themultiple point HO. Radio bearer processing unit 1424 is configured tomake changes to parameters, such as RRM/QoS parameters, of radiobearers. A HO processing unit 1426 is configured to determine a need fora multiple point HO according to the measurement reports received fromthe UEs or communications points. HO processing unit 1426 is configuredto generate messages to perform the multiple point HO. A data processingunit 1428 is configured to process received data and split the receiveddata if necessary and forward the received data to the UEs orcommunications points according to radio bearer configuration. A memory1430 is configured to store received data, measurement reports, radiobearer configurations and/or parameters, security information, and thelike.

The elements of communications device 1400 may be implemented asspecific hardware logic blocks. In an alternative, the elements ofcommunications device 1400 may be implemented as software executing in aprocessor, controller, application specific integrated circuit, or soon. In yet another alternative, the elements of communications device1400 may be implemented as a combination of software and/or hardware.

As an example, transmitter 1405 and receiver 1410 may be implemented asa specific hardware block, while measurement report processing unit1420, security information generating unit 1422, radio bearer processingunit 1424, HO processing unit 1426, and data processing unit 1428 may besoftware modules executing in a processor 1415, a microprocessor, acustom circuit, or a custom compiled logic array of a field programmablelogic array.

Although the present invention and its advantages have been described indetail, it should be understood that various changes, substitutions andalterations can be made herein without departing from the spirit andscope of the invention as defined by the appended claims.

What is claimed is:
 1. A method for operating a multiple point (MP)controller, the method comprising: receiving, from a source primarypoint, a handover required message for a user equipment coupled to thesource primary point, the handover required message including targetprimary point information and MP radio bearer information for an MPradio bearer; determining an MP configuration according to the handoverrequired message; sending, to a target primary point, a handover requestmessage including the MP configuration and the MP radio bearerinformation; sending, to the source primary point, a handover messageincluding the MP configuration, the MP radio bearer information, andreconfiguration information for the user equipment, the handover messageinitiating a handover of a subset of the MP radio bearer from the sourceprimary point to the target primary point; and receiving, from thetarget primary point, a handover complete message indicating completionof the a handover, the handover complete message including an update tothe MP radio bearer information; and sending, to the source primarypoint, a handover message including the MP configuration, the MP radiobearer information, and reconfiguration information for the userequipment, the handover message initiating the handover of a subset ofthe MP radio bearer from the source primary point to the target primarypoint.
 2. The method of claim 1, wherein the handover required messagealso includes target primary point security information.
 3. The methodof claim 1, wherein determining the MP configuration comprises: changinga first MP radio bearer configuration for the source primary pointaccording to the MP radio bearer information; and changing a second MPradio bearer configuration for the target primary point according to theMP radio bearer information.
 4. The method of claim 1, wherein thehandover required message further comprises non-MP radio bearerinformation for a non-MP radio bearer, and wherein determining the MPconfiguration further comprises: removing the non-MP radio bearer fromthe source primary point; and adding the non-MP radio bearer at thetarget primary point.
 5. The method of claim 1, wherein the MP radiobearer information includes an identifier of the MP radio bearer, and aparameter of the MP radio bearer.
 6. The method of claim 5, wherein theparameter comprises a radio resource management parameter, a Quality ofService parameter, or a combination thereof.
 7. The method of claim 1,wherein the handover request message also includes target primary pointsecurity information.
 8. The method of claim 1, wherein the handovermessage also includes remaining MP radio bearer information for aremaining MP radio bearer that is retained at the source primary pointafter completion of the handover.
 9. The method of claim 1, wherein thereconfiguration information includes user equipment identity informationassigned to the user equipment at the target primary point, userequipment security information at the target primary point, the MP radiobearer information, remaining MP radio bearer information for aremaining MP radio bearer that is retained at the source primary pointafter completion of the handover, or a combination thereof.
 10. Themethod of claim 1, wherein the handover complete message includes anupdate to the MP radio bearer information.
 11. The method of claim 1,further comprising sending, to a secondary point, a second handovercomplete message indicating completion of the handover.
 12. A multiplepoint (MP) controller comprising: a receiver configured to receive, froma source primary point, a handover required message for a user equipmentcoupled to the source primary point, the handover required messageincluding target primary point information and MP radio bearerinformation for an MP radio bearer, and to receive, from a targetprimary point, a handover complete message indicating completion of ahandover, wherein the handover complete message includes an update tothe MP radio bearer information; a processor operatively coupled to thereceiver, the processor configured to determine an MP configurationaccording to the handover required message; and a transmitteroperatively coupled to the processor and to the receiver, thetransmitter configured to send, to the target primary point, a handoverrequest message including the MP configuration and the MP radio bearerinformation, and to send, to the source primary point, a handovermessage including the MP configuration, the MP radio bearer information,and reconfiguration information for the user equipment, the handovermessage initiating a handover of a subset of the MP radio bearer fromthe source primary point to the target primary point.
 13. The MPcontroller of claim 12, wherein the processor is configured to change afirst MP radio bearer configuration for the source primary pointaccording to the MP radio bearer information, and to change a second MPradio bearer configuration for the target primary point according to theMP radio bearer information.
 14. The MP controller of claim 12, whereinthe handover required message includes non-MP radio bearer informationfor a non-MP radio bearer, and wherein the processor is configured toremove the non-MP radio bearer from the source primary point, and to addthe non-MP radio bearer from the source primary point to the targetprimary point.
 15. The MP controller of claim 12, wherein thetransmitter is configured to send, to a secondary point, a secondhandover complete message indicating completion of the handover.
 16. TheMP controller of claim 12, wherein the handover required message alsoincludes target primary point security information.
 17. The MPcontroller of claim 12, wherein the MP radio bearer information includesan identifier of the MP radio bearer, and a parameter of the MP radiobearer.
 18. The MP controller of claim 17, wherein the parametercomprises a radio resource management parameter, a Quality of Serviceparameter, or a combination thereof.
 19. The MP controller of claim 12,wherein the handover request message also includes target primary pointsecurity information.
 20. The MP controller of claim 12, wherein thehandover message also includes remaining MP radio bearer information fora remaining MP radio bearer that is retained at the source primary pointafter completion of the handover.
 21. The MP controller of claim 12,wherein the reconfiguration information includes user equipment identityinformation assigned to the user equipment at the target primary point,user equipment security information at the target primary point, the MPradio bearer information, remaining MP radio bearer information for aremaining MP radio bearer that is retained at the source primary pointafter completion of the handover, or a combination thereof.
 22. The MPcontroller of claim 12, wherein the handover complete message includesan update to the MP radio bearer information.